The present invention relates to microfilm-reading and enlarging apparatus in general, and more specifically to a control device for adjusting the width of a diaphragm slot in the diaphragm of the microfilm-reading-and-enlarging apparatus.
In the microfilm-reading-and-copying apparatus of the foregoing type an enlarged microimage is projected in image columns by means of two mirrors, inclined at 45.degree. to the optical axis of the projection lens, and the diaphragm having a slot onto a copying drum or cylinder. The two mirrors are positioned on a movable carriage which is moved synchronously with the copying drum.
In such known apparatus the decrease in light intensity or luminosity of the image being copied in the regions of its edges in the direction of transportation of the scanning device or the copying drum or the copy paper is compensated for by an electronic adjustment of the light intensity of the illumination system in dependence on the position of the carriage on which the above mentioned mirrors are disposed.